Parrot's feather (Myriophyllum aquaticum)

Parrot's feather is a common weed in coastal waterways of eastern Australia.

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How does this weed affect you?

Parrot's feather is a semi-submerged aquatic weed that grows in coastal waterways of eastern Australia. It is native to South America and widespread around the world. It can form dense stands within a waterbody, impeding water flow and altering natural habitats. 

Where is it found?

Parrot's feather occurs in coastal areas from Brisbane to Sydney. 

How does it spread?

In Australia, parrot's feather spreads by fragments. Male and female flowers are produced on separate plants. Only female plants have been found in Australia, and therefore seeds are not produced. If male plants were introduced to Australia, this species could become more prolific.  

What does it look like?

Parrot's feather is a feathery submerged water plant, with some stems above the water (emergent). It has whorls of feather-like leaves. The submerged leaves are up to 4 cm long, while the emergent leaves have a blue-green appearance, are toothed, 2.5-3.5 cm long, and crowded at the tips of stems.

The flowers are inconspicuous, and occur in the leaf axils (the junction between the stem and the leaves) on emergent stems.

Stems are spreading, erect and hairless. 

Similar looking species include ambulias (Limnophila spp.), cabomba (Cabomba caroliniana) and other Myriophyllum species. 

Habitat

Parrot's feather grows very well in nutrient-enriched water, in still or slow-moving bodies of fresh water in coastal areas of eastern Australia. 

References

New South Wales Industry & Investment (2009) Recognising Water Weeds - Plant Identification Guide, Orange.

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Control

Physical removal is recommended where appropriate. Draining a waterbody and allowing the parrot's feather to dry out can afford control. Contain infestations wherever possible to avoid further spread resulting from the movement of plant fragments.

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


Dichlobenil 40 g/kg (Casoron 4G Herbicide)
Rate: 2.9 to 3.9 kg per 10m2
Comments: Exposed soil. DO NOT apply to water which will be used for crop irrigation, for livestock watering, or for human consumption.
Withholding period: Do not graze livestock on treated areas.
Herbicide group: O, Inhibitors of cell wall (cellulose) synthesis
Resistance risk: Moderate


Dichlobenil 40 g/kg (Casoron 4G Herbicide)
Rate: 287 to 388 kg per ha or 2.87 to 3.88 kg per 100m2
Comments: Water less than 1m deep. Apply when weeds are dormant. DO NOT apply to water which will be used for crop irrigation, for livestock watering, or for human consumption.
Withholding period: Do not graze livestock on treated areas.
Herbicide group: O, Inhibitors of cell wall (cellulose) synthesis
Resistance risk: Moderate


Dichlobenil 40 g/kg (Casoron 4G Herbicide)
Rate: 388 to 574 kg per ha or 3.88 to 5.74 kg per 100m2
Comments: Water more than 1 m deep. Apply when weeds are dormant. DO NOT apply to water which will be used for crop irrigation, for livestock watering, or for human consumption.
Withholding period: Do not graze livestock on treated areas.
Herbicide group: O, Inhibitors of cell wall (cellulose) synthesis
Resistance risk: Moderate


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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area Duty
All of NSW General Biosecurity Duty
All plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.

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Reviewed 2018